Utilization of a gas chromatograph-mass spectrometer-computer system in pharmacological research is proposed in this grant application. The GC-MS-computer system will be used to characterize the organic acids appearing in the plasma and urine of primates which have been treated with toxic quantities of methanol, ethylene glycol, and 2- methoxyethanol. Other investigations involve the use of stable isotopes in conjunction wtih mass spectrometry. A sensitive and accurate mass spectrometer-computer method for the analysis of H sub 2 super l8 O will be developed so as to measure body water in the newborn infant by isotope dilution. This method will be used to compare total body water and extracellular water in a group of low-birth-weight infants fed normal amounts of protein, and supplemental protein intakes. GC-MS- computer procedures will be developed to quantitate extremely small amounts of neuropharmacologically significant molecules: tyrosine, dopamine, norepinephrine, adenine nucleotides, and biopterin. These compounds will be measured with the aid of stable isotopically-labeled molecules serving as both carrier and internal standard. Studies will be performed to investigate the correlation between behavior and the release of catecholamines from areas of the brain of animals treated with amphetamine, as well as the development of a sensitive technique for the measurement of adenine nucleotides released following adrenergic nerve stimulation.